Taiwan Patent Publication No. 485221 discloses a continuously stepless speed-changing gear set, which mainly includes an input shaft, a high-speed gear set, a low-speed gear set, an output shaft, a first differential device connecting the input shaft to a driving wheel in the high-speed gear set and a driving wheel in the low-speed gear set, and a second differential device connecting the output shaft to a driven wheel in the high-speed gear set and a driven wheel in the low-speed gear set. Since the above-described conventional speed-changing gear set uses meshed gears to transmit force, it requires addition of heat-radiating oil to reduce a high amount of heat produced by gears at their contact points due to friction.
It is therefore tried by the inventor to develop an automatic stepless speed-changing mechanism to eliminate the drawbacks existed in the conventional stepless speed-changing gear set.